The present invention is drawn to an improved ceramic foam material and process for making same and, more particularly, a ceramic foam material having superior mechanical, thermal and chemical properties than ceramic foam materials heretofore known.
It is known in the art to employ porous ceramic foam materials to filter molten metal, especially aluminum, as described for example in U.S. Pat. Nos. 3,893,917, 3,947,363, 3,962,081, 4,024,056, 4,024,212, 4,075,303, 4,265,659, 4,342,644 and 4,343,704. The production material for these filters comprises primarily a phosphate bonded refractory material, having certain other additions, which has been fired to a temperature of about 2000.degree. F. in order to mature the bond. See the process described in U.S. Pat. No. 3,962,081. While this type of refractory is suitable for use in the aluminum industry and easily withstands most aluminum alloys which are typically cast at about 1300.degree. F., it is unsuitable for many other potential applications due to its low strength and poor chemical durability. Naturally, it would be highly desirable to develop a material which maintains the favorable properties of the ceramic foam materials heretofore known, namely, high porosity, low pressure drop, high geometric surface area and tortuous flow path, but which overcomes the above-noted difficulties of strength and chemical durability. In addition, it would be desirable to develope a single material which could be relatively simply produced and used in a number of applications, especially for use in high temperature applications, such as with ferrous metals and especially in filtration applications.
Accordingly, it is a principal object of the present invention to provide an improved ceramic foam material and process for making same.
It is an additional object of the present invention to provide an improved ceramic foam material characterized by superior strength and chemical properties as well as improved mechanical and refractory properties.
It is a further object of the present invention to provide an improved ceramic foam material which is relatively simple to produce.
It is a still further object of the present invention to provide a ceramic foam material suitable for numerous diverse applications, such as for ferrous filtration.
Further objects and advantages will appear hereinbelow.